The Effect of Wetf Exposure onthe Tensile Overlap Shear Strength of Epoxy/Fiberglass Composite Bonded To Stainless Steel Using a Toughened Epoxy Paste Adhesive

摘要

The Extravehicular Mobility Unit (EMU) or Shuttle spacesuit is used by NASA for astronaut training inthe Weightless Environment Training Facility (WETF). The WETF enviornment is significantly different from the space environment the suit expweriences in service. Prolonged exposure to this warm, wet environment has been shown to degrade the adhesive joints inthe Hard upper Torso Shell (HTS). This paper presnts the results of a 16 week exposure to a simulated WETF environment of the new Planar HTS materials of construction; Fiberite MXB 7701/7781 epoxy fiberglass composite bonded to 347 stainless steel using Hysol XEA 9360 toughened epoxy paste compared with the existing pivoted HTS design which uses Hysol EA 934 NA epoxy to bond Hitco P604C polyester fiberglass composite to chrome plated stainless stell. The results show a dramatic improvement inthe initial lap shear stength of the new HUT materials compared to the existing materialsl Exposure to the WETF environment resulted ina gradual decline in strength that was associated iwth a change in failure mode from cohesive to adhesive at the stainless stell interface.